Technical Field
The inventions relate to measuring syndromes of quantum redundancy coded states, which may have undergone physical degradation.
Related Art
This section introduces aspects that may be helpful to facilitating a better understanding of the inventions. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.
Since information carrying entangled quantum states are susceptible to errors during some types of physical processing, error-correction will probably be used by quantum computers, in which such entangled quantum states carry information. In such quantum computers, the error-correction may involve quantum redundancy coding of the information carrying entangled quantum states based on quantum stabilizer groups.
Quantum redundancy coding involves coherently mixing the individual initial quantum states, i.e., information carrying states, with a preset quantum state thereby producing corresponding quantum redundancy coded states. The coherent mixing typically entangles each initial quantum state with a preset quantum state having multiple quantum bits (qubits). After quantum redundancy coding, physical processing may generate errors in the quantum redundancy coded states. The physical processing may include, e.g., transmission of the quantum redundancy coded states over a physical communication channel and/or storage of the quantum redundancy coded states.
After the physical processing, the physically processing processed quantum redundancy coded may be subjected to error-correction processing. The error-correction process typically involves measuring a value of the syndrome of a physically processed quantum redundancy coded state. The measured value of the syndrome is indicative of whether an error has been produced in the corresponding quantum redundancy coded state by the physical processing. Typically, the measured values are used to identify the errors, which are most probably produced by the physical processing. If the measured value of the syndrome indicates the presence of an error, the error-correction process may involve applying a quantum operation to the physically processed redundancy coded quantum state to invert the error most likely produced by said physical processing. The form of the applied quantum operation is determined from the syndrome of the physically processed quantum redundancy coded state. Usually, the set of errors correctable by such error-correction processing is a proper subset of the set of all errors that the physical processing can produce.